A study of the lead dioxide electrocrystallization mechanism on glassy carbon electrodes. Part I: Experimental conditions for kinetic control

The dependence on chemical and electrochemical variables of lead dioxide electrodeposition on a glassy carbon electrode from Pb(II) aqueous solutions has been studied. Depending on the experimental conditions, the mechanism of lead dioxide electrodeposition may involve kinetic or mass transport control. Both modeling and morphological studies of the nucleation and growth process have been carried out. The analysis of the chronoamperometric curves obtained from potential step experiments required a previous study regarding (i) the experimental solution conditions (pH, Pb(II) concentration), (ii) range of the final step potential to be used, and (iii) the choice of theoretical models used to obtain the kinetic parameters. Direct microscopic observation of the electrode through the initial stages of oxide phase formation has provided independent values of nucleation kinetics parameters (N0A), growth constants (k), induction time (t0) and their dependence on the electrochemical variables. The fitting of the experimental curves using some of these independent values allowed other ones, with more realistic values, to be obtained. Further discussion on the mechanistic details of the lead dioxide electrodeposition is presented.